Conversion of hydrocarbons



June 11, 1940, Fyw. LEFFER 2,203,829

` COVERSICN 0F HYDROCARBONS 1 caa/yar 7km@ Unia; 6.9, 70

AUNITED 'STATI-:s PATENT oFl-lc CONVERSION OF HYDROCABBONS Friedrich W.Leffer, Kenton-Harrow, England, assignor to Universal Oil ProductsCompany, Chicago, lll., a corporation of y Delaware Application October2.1, 1937, Serial No. 170,186

4 Claims. (Cl. 196-10) This invention relates particularly .to theconmethods of chemical treatment best suited to the version of theheavier fractions of petroleum cracked and polymer fractionsrespectively.

and analogous fractions `from other hydrocar- In one specifcembodimentthe present invenbonaceous materials into substantial yields of tioncomprises cracking hydrocarbon oil mix- 5 high antiknock lmotor fuel.tures to produce material yields of gasoline and 5 In a still more speccsense the invention is olen containing gases, fractionating the gasolineconcerned with processes wherein heavyhydrointo light and heavy portionsrespectively, treatcarbon mixtures are subjected to pyrolyticgconingsaid heavy portions with sulfuric acid to ditions of temperature andpressure to produce improve their quality, subjecting the gases andgases containing appreciable percentages of the lighter gasolinefractions to contact with 10 olenic hydrocarbons, liquid motor fuelfracphosphoric acid containing catalysts to effect tions, intermediateinsuiiiciently converted fr'acpolymerization, alkylatien and treatingreactions, tions suitable for,further subjection to pyrolysisstabilizing the products of these reactions to a and heavy residueswhich are unsuitable theregiven Vapor pressure, treating the Stabilizedfor. It is a particular object of the present material with relativelymild chemical reagents, l5 invention to utilize the olefnic content Vofthe blending the treated material With the Slllfinie iixed gases toproduce additional yields of liquid acid-treated heavier fractions ofthe gasoline and motor fuel fractions and to selectively treat by Afraetionating the blended-material t0 Produce a suitable chemicalprocesses the heavier and the rened high antiknoek motor fllel aS theProduct lighter fractions respectively'of the motor fuel 0ftlle`pl0eeSS- 20 fractions produced both in the primary pyrolysis In analternative embodiment the gases and and in the subsequent selectivepolymerization lighter gasoline fractions are ISt Separated by step.condensing the former, the separated gases are In accordance with theneed for increased Separately eOntaeted With PhOSPhl'iCacid-00nefficiency in the utilization of petroleum and partainingcatalysts at temperatures and rates 25 ticularly in Athe more eflcientutilization 0f the favorable to the selective polymerization of theirproducts from the cracking of petroleum, conbutylene content, thebutylene Polymers are siderable research is being .devoted to thedeseparated from the residual gases and the revelopment of processeswhich will effectively re- VaDOliZed light gasoline fl'aCtGnS areSeparately no convert at least a portion of the. gaseous bycontactedwith phosphoric acid-containing cata- 3o products of cracking back intonormally liquid lYStS along With the ledllal gases. hydrocarbonsutilizable as motor fuel. At the The various cooperative features 0f thepresent present time these developments have reached process whichrender it novel and usefulfrom a the stage of utilizing the oleflniccontent of the COInmeiCial standpoint Will be `devel0ped in as crackedgases by subjecting them to polymerizagreater detail br following acharacteristic tion processes, the majority of which'are effectiveDIOCeSS lOW in Connection with the attached in converting the majorportion of the propylene drawing Which ShOWS in general Side elevationand butylenes without much'eifectupon the ethylby the 115e 0fConventional figures an arrangel ene content although this may beequivalent in ment 0f apparatus in Which the DI'OCeSS may be 40 volumeto the total of the 3 and 4 carbon conducted. In the development of theprocess, 40 atom hydrocarbons mentioned. Strictly thermal Severalalternative modes 0f Operation 'Will be methods of polymerization s Wen'as those em; shown which are all comprised within the general ployingspecic catalytic materials are in comscope of the inventmn' mercial useand are apparently-still on -a com- Referrfng to ,the drawmg u ne lcontammg petitive basis. The present process, the fea- Valve 2 15 shownas an Inlet Ime. for vaporous 45 tures of which will be developed in thefollowing cracted 'products to a' mm1 frf'ctwnatr 3 the details of thecracking operation having been specification, embodies 4an improvement1n .tted as constitutin ia] f t f th methods of catalytic polymerizationof the cm1 g no spec ea' me o e e, Y present invention since thevaporous products lighter Olenlc hYdUCalb'UP Prodllcfd m Crack frompractically any commercial type of cracking 50 mg hydrocarbon oils,utilizing particular ltypes process may be subjected to the present typeof 0f Catalytic' mammals an@ Selected Condll'llfms treatment.Fractionator 3 is preferably divided of treatment for the varwusOlean-contalmne bye eappedeolleeting plate 5 into upper sectionfractions both of the gases and the motor fuel 4 and lower section 6,the lower section having 55 boiling range liquids, While applying alsoselected a draw line l containing valve 8 for the removal 55 ofintermediate fractions which usually are returned to the crackingprocess to undergo further conversion in admixture with the originalcharging stock.

According to the present process, the fractionation is s`o conductedthat only gasesl and gasoline boiling range materials are admitted tosection 4, the heavier portions of the gasoline accumulating` oncollecting plate 5 and being continuously withdrawn therefrom through aline containing valve 8| to an appropriate type of chemical treatmentwhichV will be subsequently described. The vapors from upper section 4of fractionator 3 will comprise the total fixed gases and the lowerboiling constituents of the gasoline product which will have a boilingrange depending upon such factors as the type of oil originally cracked,the conditions of cracking, the hydrocarbon group content of the lightfraction, particularly in regard to olens and other more reactivehydrocarbons, the nature and proportioning of the olens in the fixedgases and the character desired in the finished product of the process.In other words, it will be a matter of trial in dierent cases todetermine the best segregation between the light and heavy gasolinefractions.

At this point several alternative modes of procedure are possible. Inone case the total mixture of gases and light gasoline fractions may besubjected to a catalytic treatment aimed at ef` fecting polymerizationand other types of reactions among the hydrocarbons including a refiningaction, while utilizing a portion ofthe condensible overhead fractionsto assist in controlling the boiling range of the overhead products. Inanother alternative mode of operation the light gasoline fractions arecondensed and separated from the fixed gases, the gases are thenseparately subjected to catalytic polymer--A ization for the removal ofa portion of the more readily polymerizable olens and the residual gasmixture containing unconverted gaseous oleiins are then admixed with therevaporized light gasoline fractions and subjected in admixture toseparate catalytic action to produce reactions of a different characterall aimed atv the selective utilization of the gaseous olens to produceincreased yields of gasoline.

Thus in one instance the total products from the top of fractionator 3may be passed through line 9 containing valves I0 and II to contact withsolid polymerizing catalysts whose manufacture and properties will bedescribed later, said catalytic material' being contained in treaters 3Iland 34 connected by a line 32 containing a valve 33, these two treatersrepresenting any number .which may be employed in series connection foreffecting the desired polymerization reactions. In this'type ofoperation a suflicient amount of the overhead products may be divertedto undergo partialcondensation and produce an overhead reflux to; assistin controlling the boiling point of the overhead fraction, said divertedstream following line I2 containing valve I3, condenser I4, run downline I5 containing valve I6 and entering receiver I1 from which thecondensed liquids are withdrawn by pump 20 through line I8 containingvalve I9 and returned by way of line 2I containing valve, 22 and line 23containing valve 24 to the upper portion of the fractionator. The gasesaccumulating in re-" ceiver If1 are then taken by pump or compressor 28through line 26 containing valve 21 and-disto line 9 and-thence intocontact with the polymerizing catalyst. l

It is a feature of the present process that the first polymerizing unitcomprising as shown in the drawing towers 3I and 34 should be operatedat relatively low temperature to effect the selective polymerization ofthe more readily polymerizable olens in the gases and in the lightgasoline fractions, `the preferred temperature range when usingtheparticular catalysts characteristic of the invention being of theorder of from to 120 C. At this temperature and under the normalpressures of such polymerizing process which normally range fromapproximately to 300 lbs. per square inch, there is a more or lessselective polymerization of the butylenes and particularly isobutylene,so that there is produced a relatively high yield of o ctenes from thebutylenes present in the gases. also be some polymerization of theolenic content of the light gasoline fraction so that in effect there isa. general rise in the boiling point range.

In order to bring the mixture of gases and light gasoline vapors to theproper temperature for treatment in the primary catalytic unitcomprising chambers 3| and 34, a cooler is provided since obviously incase the mixture is brought directly. from the fractionator of thecracking plant with diversion only of a suflicient portion of themixture to furnish rellux for the fraction-v ating column, thetemperature will be higher than desired since it may vary fromapproximately to 260 C. depending upon the pressure obtaining at the topof the fractionator and the average boiling range of the emergentgasvapor mixture. In order to reduce the temperature to within theapproximate range specied above, any required portion of the gas-vapormixture may be diverted through line I3 and valve I2' through cooler I4'and back into line 9 by way of line I5 containing valve I6. 'I'he coolermay be cooled by air or any other fluid or liquid which is suitable foreifectingtthe required reduction in temperature. Obviously, sometemperature reduction is Aeffected in the total ga'svapor mixture by thecondensation of the required reflux since the residual gas mixturepassing through line 29 back to line 9 will be at ap- Amerizing stepfollow line 35 containing valve 36 and pass through a condenser 31 whichhas a rundown line 38 containing valve 39 and leading to a receiver 40which functions as a separator for the liquid and gaseous products, thefurther treatment of which will be presently described. In analternative mode of operation the products from the fractionator are allpassedthrough line I2 and valve .I3 with valve II in line 9 closed sothat the normally gaseous and the normally liquid products are separatedin receiver I1 and separately contacted with the catalyst. In this casethe gases follow line 26, valve 21, pump 2'8, line 29 and valve 30 tothe primary polymerizing unit as before but without admixture withy thenormally liquid lightgasoline fractions. By this procedure theconditions necessary for effecting maximum polymerization of thebutylene content of`the gases may be more accurately defined andproducts containing a higher percentage of Ioctenes (which are readilyhydrogenatable to There will I butylene (and particularly theisobutylene) con- 75 aaoaeea y tent of the gases and the proportioningof the different groups of hydrocarbons in the gases and the lightgoline fractions. Obviously when all of the gas-vapor mixture from line9 is subjected to cooling in condenser` I4, the Yresidual gases willrequire reheating to the optimum temperature for the polymerization ofthe more readily polymerizable olefins although means for accomplishingthis reheating are not shown in the drawing.

In this second method the vapors of the light gasoline fractions arevsubjected to catalytic/action along with the residual gases from theprimary polymerizing step, that portion of the gasoline vapors notneeded for fractionation control passing along line 2| through valve 21'to the second treating unit comprising treaters 5| and 54 connected byline 52 containing valve 53 and representing as in the case of theprimary unit any desired number and arrangement of treatingV towers.Since the light gasoline fractions passing through line 2| to the secondcatalytic treating unit will require vaporizing and heating to anoptimum temperatureV for treatment, a portion or all thereof may bediverted through line 22 and valve 23' to heater 24 and back to line 2|by way of line 25' containing valve 26' with proper setting of valve 21to cause the required diversion. The residual gases from receiver followline 46 containing valve 41 to pump or compressor 48 and are disactivehydrocarbons in the light gasoline frac-y tions which may comprise nandiso-olefins, cyclo olens and aromatics depending upon the nature ofthestock originally cracked and the intensity or fdepth of the crackingprocess. By

utilizing the higher temperatures in the second treating unit theoptimum utilization of the more diiiicultly polymerizable olens and thetreating of the light gasoline fractions for the removal of more highlyunsaturated gum-forming hydrocarbons is advantageously effected.

The total products from the reactions in the second treating step leaveiinal treater 54 through line 55 containing valve 56 and pass through ausually little tendency for gas accumulations at condenser 51 which hasa line 58 containing valve 59 leading therefrom to a receiver 60 whichfunctions as a gas-liquid separator and permits the withdrawal of gasesthrough line 66 containing valve 61, the gases at this point consistingprincipally of ethane, ethylene, methane, hydrogen, and other gases suchas hydrogen sulfide in case this was present in the primary gas mixture.

The liquid prbducts from both treating units are now blended andstabilized, those from receiver' 40 passing through line 4| and valve 42to pump 43 which discharges into line 44 containing valve and leading tostabilizer 68, while those liquid products accumulating in receiver 60are removed through line 6| containing valve m L62 and taken by pump 63to be discharged through atom hydrocarbons and a suicient-quantity of fthe l-carbon atom hydrocarbons to reduce the `a sufficient temperatureto cause the effective fractionation and separation of the undesirable3- and 4-carbon atom hydrocarbons which are evolved through line 69 andvalve 10 to whatever disposition may be desired. The stabilized poly`mer products follow line 12 containing valve 13, pass through cooler 14and thence through run down line 15 containing valve 16 to a pump 11which discharges into a line 18 containing a valve 19 and leading to thesecond chemical treating unit to be presently described.

The primary chemical treatment consists in the application of'sulfuricacid to the heavier gasoline fractions which leave cracking plantfractionator 3 from collecting plate 5 and follow line 00 containingvalve 8i to the yreceiver 82 which has a conventional gas release line83 containing a valve 84. The liquid is taken by pump 81 through line 85containing valve 86 which discharges through line 88 containing valve 89into some type of mixer or agitating device 92 after having received anaddition of sulfuric acid through line 90 containing valve 9|, theamount and concentration of the acid being selected to `,produce thebest overall treating effect when considering the chemical`characteristics of the heavier fractions. The mixture of treated oil andsludge acid passes through a line 93 and valve 94 to a separator95 fromwhich sludge is drawn through line 96 and valve `91, the treatedfraction still somewhat acid passing through a line '98 containing valve99 toa water washing tower |00 into which a water ,spray is introducedthrough line |03 containing valve |04. and from which acid wash water isdrawn from the bottom of the tower through line |0| containing valvey|02. The washed and possibly slightly acid stock is then passed throughline |05 containing valve |06 to a pump |01 which discharges through aline |08 containing a valve |09 to line ||6 leading to the mixing deviceof the second chemical treating unit.

The second unit is operated primarily to give a light treatment to theproducts from the catalytic treating `units which accumulate in thereceiver ||0 having a conventional gas release line |l| containing avalve ||2 although there is this point.

The liquid polymer products taken through line |3 containing valve Hlare discharged by pump l|5 through line H6 containing valve lil andthence into the mixer of theA secondary unit after receiving the primaryacid treated and washed heavier fractions from line |06 and a deniteamount of alkali (usually caustic soda) from line ||9 contain-ing valve|20.v As a rule the alkali treatment is all that is necessary forrefining thevpolymerproducts and suiiiciently neutralizing the a'cidtreated stock. If the polymer product contains appreciable percentagesYof mercaptans and is sour to the doctor test, a-

plumbite or other sweetening method may be substituted with suitablemodication of the subsequent treating equipment. Ii desired, althoughnot shown in the drawing, the acid treated fraction from the primarychemical treating unit may cel be separately neutralized althoughprovision for gs an inlet water spray'and a line |30 containing a valve|3| for drawing olf wash Water.

As a final step in the process the blended and treated productsarefractionated to produce a gasoline of desired boiling range. Thus thefinally washed blend is withdrawn from the top of tower A|29 throughline |34 containing valve and forced by pump |36 through a line |31containing Valve |38 through a heater coil |30' which serves to bring.the products up to atemperature which will insure their properfractionation. The heated material passes through line |39 containingvalve |40 to a final fractionator |4| from'which the desired gasolineproduct is taken overhead in vapor form, the vapors following line |44containing valve `|45 and passing through condenser |46 and liquidrundown line |41 containing valve .|48.to flnalreceiver |49 which has aconventional gas release line |50 containing a valve |5| and a draw line|52 containing a valve |53 for finished product. Heavy productsseparated in'fractionator |4`| are withdrawn throughl line |42 havingvalve |43.

The catalytic. treating material preferably employed in the catalytictreating units described above comprises preferably a granular compositeproduced by primarily incorporating a phosphoric acid with a relativelyinert carrying material such as kieselguhr, heating the primary pastymix to a temperature of the order of 300 C. or higher to produce 4asolid cake, grinding and sizing the cake to produce particles ofapproximately 6-20 mesh and if found necessary subjecting the granularparticles to the actionv of superheated steam at a temperature of theorder of 260 C. under atmospheric pressure to produce the optimum degreeof hydration. The above procedure may be modifled by forming theoriginal pasty mix either by extrusion or pelleting methods andcalcining and steaming the forms.

somewhat greater degree of hydration than the l pyro acid. and evidentlysome Silico-phosphoric acid complexes which have some catalytic andtreating activity and furnish a support for the more active phosphoricacid constituent. -Materials of`l this character have been found to ber500" C. it is practically always necessary to rehydrate the particlesas in the method of manufacture and reactivated materials are frequentlyfound to have higher catalytic activity than freshly prepared catalysts.

The following example is given to indicate the character'of the resultsobtainable by the use of the process although not with the intention ofcorrespondingly limiting its scope.

A gas oil fraction representing an intermediate c'ut from a mixed crudeoil from the Mid-Continent area was cracked at a temperature ofapproximately 500 C. in the cracking lzoneunder a pressure ofapproximately 350 lbs. per sq. in.,- the vapors being fractionated inaccordance with the scheme outlined in the preceding process descriptionso that approximately the lighter half of the gasoline boiling rangematerial was removed from the top of the fractionator along with thenormally gaseous products while the w heavier half was removed from theupper section of the fractionator and passed directly to sulfuric acidtreatment. The overhead in the fractionator was cooled and the lightgasoline vapors condensed. The residual gas mixture was reheated to atemperature of approximately C. and passed through a series of chamberscontaining solid phosphoric acid catalysts to polymerize substantiallyall of the isobutylene content and a portion of the normal butylenes.The portion of the condensed light gasoline fraction not required asreflux at the top of the fractionating column was reheated to atemperature of approximately 260 C. and mixed with therepolymers plusvsecondary polymers and treated light gasoline vapors were combined andstabilized to a 10 lb. Reid vapor pressure.

The higher boiling 50% of the gasoline was treated with sulfuric acid atthe rate of approximatelyf lbs.y per 42 gallon barrel and the stabilizedmixture of polymers and treated light ends were treated Awith 10 B.caustic soda in admixture with the washed heavy fraction.

The net result of -the foregoing series of operations was the productionfrom the original gas oil of 65% by volume of 400 F. end point gasolinehaving an octane number of '12 by the-motor method and passing allspecications in respect to gum and sulfur content.

The character of the present invention and its novelty and utility inthe petroleum rening art can be seen from the preceding specificationand numerical sections although neither is intend/ed to be undulylimiting.

I alaim as my invention:

1'. A process for treating the mixture of gasoline vapors and normallyincondensable gases produced in the cracking of hydrocarbon oil, whichcomprises separating said mixture into a heavy gasoline fraction, alight gasoline fraction and a'gaseous fraction, subjecting said heavygasoline fraction to a refining treatment with sulfuric acid, subjectingsaid gaseous fraction tocontac't with a phosphoric acid-containingcatalyst to effect selective polymerization of the butylenes thereincontained, condensing and separating liquid polymers fromunconvertedgases, combining the latter with 4said light gasoline fraction andsubjecting the resultant mixture to separate contact with a phosphoricacid-containing catalyst to effect' further polymerization and treatmentof the mixture, stabilizing gasoline boiling products of both saidpolymerizing stages in admixture, combining the stabilized mixture withthe acid treated heavy gasoline fraction and subjecting the resultantblend to treatment with alkaline materials.

2. A process for treating the mixture of gasoline vapors and normallyincondensable gases produced in the cracking of hydrocarbon oil, whichcomprises separating said mixture into a heavy gasoline fraction,v alight gasoline fraction and a gaseous fraction, lsubjecting said heavygasoline fraction to a rening treatment with sulfuric acid, subjectingsaid gaseous fraction to contact with a phosphoric acid-containingcatalyst at temperatures of the order of 90 to 120 C. to effectselective polymerization of the butylenes therein contained, condensingand separating liquid polymers from unccnverted gases, combining thelatter with said light gasoline fraction and subjecting the resultantmixture to separate contact with a phosphoric acid-conn taining catalystat temperatures of the order of 150 to :Z50` C. to eiect furtherpolymerization and treatment of the mixture, stabilizing gasolineboiling products of both said polymerizing stages in admixture,combining the stabilized mixture with the acid treated heavy gasolinefraction and subjecting the resultant blend to treatment with alkalinematerials.

3. In the cracking' of hydrocarbon oil wherein gasoline distillate isseparated from normally incondensable gases l containing butenes andpropene, the method which comprises subjecting the separated gas topolymerization under conditions suitable for selective polymerization ofbutenes, separating resultant butene polymers from the residualpropene-containing gas, combining the latter with at least a portion ofsaid gasoline distillate, including the lighterfractionsthereof, andsubjecting the resultant mixture to propene polymerizing conditions.

4. A process for treating the mixture of gasoline vapors and normallyincondensable gases produced in the cracking of hydrocarbon oil,

which comprises separating from said mixture a heavy gasoline fraction,a lighter gasoline fraction and a normally gaseous fraction containingbutenes and propene, subjecting the gaseous fraction to polymerizationunder conditions sultable' for selective polymerization of butenes,separating the resultant butene polymers from residualpropene-containing gas, combining the latter with said lighter gasolinefraction and subjecting the resultant mixture to propene polymerizingconditions.

FRIEnRICH W. LEFFER.

